In 2021, the Government of India had stated it can transfer to twenty% ethanol mixing in petrol by 2025 with the two-pronged objective of chopping carbon emissions and lowering the nation’s dependence on overseas oil. While autos modified to be appropriate with the brand new composition began rolling out in April 2025, the federal government’s push for 20% ethanol-blended petrol (E20) has left vehicle-owners nervous in regards to the affect on their older autos and a few surge in upkeep prices.
Ethanol, or ethyl alcohol, is a biofuel: it’s constructed from plant waste known as biomass. Regular petrol is a hydrocarbon constructed from the fossilised stays of natural matter buried for thousands and thousands of years.
When combined with a fossil fuel like petrol, ethanol acts as an oxygenate that helps the petrol burn higher.
Making ethanol
Under India’s ethanol-blending programme, the federal government procures ethanol both from sugarcane-based uncooked supplies like C-heavy molasses, B-heavy molasses, sugarcane juice, sugar or sugar syrup, or broken meals grains like damaged rice, maize or cellulosic and lignocellulosic supplies.
Molasses is a byproduct of sugarcane manufacturing. It is a thick, darkish syrup about 40% wealthy in sugars that may be fermented however which might’t be extracted additional.
C-heavy molasses are the ultimate byproduct of the sugar manufacturing course of, with molasses content material round 28-32%. B-heavy molasses are an middleman byproduct of the identical course of and have the next molasses content material, round 48-52%.
Ethanol is constructed from molasses by fermentation — utilizing yeast enzymes to catalyse the breakdown of sugar molecules within the presence of water. An on a regular basis instance of fermentation is ginger soda. If you place ginger, sugar, and water in an hermetic container for just a few days, it turns into fizzy. This is as a result of the microbes in ginger feed on the sugar, releasing carbon dioxide, which makes carbonic acid with water.
In step one of ethanol manufacturing from molasses, sucrose molecules within the syrup are diluted with water. Then they break down into glucose molecules within the presence of invertase.
These glucose molecules additional react within the presence of zymase to type ethanol and launch carbon dioxide.
Producing ethanol from meals grains and lignocellulosic supplies additionally includes different processes that break them right down to fermentable sugars first. Lignocellulosic biomass is plant matter with a excessive carbohydrate content material and is normally composed of elements not used for meals or feed. This biomass is wealthy in cellulose, hemicellulose, and lignin.
Chemical nature, power effectivity
Two elements are key to understanding ethanol’s power effectivity: the calorific worth and the octane quantity.
The calorific worth of a fuel denotes its yield: the next calorific worth means extra power. The calorific worth of ethanol is considerably decrease than that of petrol, so the fuel’s general burning effectivity ought to theoretically lower. However, the federal government has maintained that the drop in fuel efficiency shouldn’t be vital and that it’s ruled by a mixture of different elements, together with “driving habits, maintenance practices such as oil changes and air filter cleanliness, tyre pressure and alignment, and even air conditioning load”.
The octane quantity is a measure of a fuel’s resistance to engine knocking or burning prematurely. Ethanol has the next octane quantity than petrol. Thus it has the potential to scale back the knock resistance considerably. However, due to its decrease power content material, the quantity of power the engine can extract per litre of blended fuel decreases with rising ethanol content material.
This stated, the drop in mileage drivers have raised issues about received’t be vital, Sudheer Kumar Kuppili, a analysis fellow at London School of Hygiene and Tropical Medicine, stated.
“The compensation for having lower energy would be quite low when you are moving from E10 to E20,” Kuppili stated. “It would be significant only when we shift to 100% ethanol. Most of the uproar these days about the reduction in vehicular mileage is fuelled by many factors, which are difficult to assess.”
In reality, specialists stated the factor to concentrate on right here is ethanol’s hygroscopic nature. That is, ethanol has a substantial tendency to draw and fasten water molecules to itself. This in flip impacts the car’s elements and fuel efficiency in new methods.
Independent knowledgeable Noble Varghese stated the principle concern is the elevated risk of corrosion.
“Ethanol affects the rubber components of a fuel system, which is mainly the piping, the fuel tank, the injectors, the filters, and the combustion chambers. The combustion chamber and the engine block itself are not as affected by ethanol, but what is affected is the fuel tank, the rubber piping, and the injector,” Varghese stated.
“Ethanol tends to attract water, so if the vehicle is not used everyday, water tends to collect in the fuel tank, which is corrosive for the tank. This causes another problem too: rust particles mix with fuel and go into the fuel line and clog it,” he added.
“That in itself will reduce the mileage. This is not primarily because of ethanol’s thermodynamic properties but more because of the components which are not suited to E20 fuel.”
The authorities has nevertheless maintained that changing older rubber elements and gaskets designed for the non-blended fuel is “inexpensive and can be easily managed during routine servicing.”
A press release launched by the Ministry of Petroleum and Natural Gas (MoPNG) on August 12 additionally stated this modification can be required solely “once in the lifetime of the vehicle” and at “any authorised workshop”.
Kuppili additionally stated moisture received’t be a big downside.
“This might be a problem for older vehicles, which are probably already worn out. This should not be a problem for BS-IV or BS-VI vehicles. The fuel’s hygroscopic nature might have a noticeable effect when you are in colder parts of the country. However, in those regions, fuels are usually mixed with additives to avoid freezing,” he defined.
“Also, when you are using a vehicle regularly, any moisture that accumulates will be evaporated by the high engine temperatures (>400º C),” he stated.
Kuppili wished to make clear that he hasn’t labored on this specific challenge of the fuels.
Comparisons with Brazil
Comparing the Indian ethanol-blending story with that of Brazil might not be justified because the South American nation presently makes use of E27 petrol in addition to paced this improve out over many years.
Brazil first determined to decrease its dependence on imported petrol in 1975 with its Proálcool programme in the course of the oil disaster within the Nineteen Seventies. Over the following few years, it centered on constructing capability by working with researchers, increasing the manufacturing of ethanol from sugarcane with the precise objective of blending it with petrol, offering subsidies, incentives, and tax breaks to scale back the prices of manufacturing, and rising the competitiveness of ethanol.
The nation additionally has a big marketplace for autos match with flex-fuel engines that enable autos to readily adapt to petrol with totally different ethanol fractions.
This isn’t the case with Indian autos. According to Varghese, the digital management unit in an engine is hypersensitive to fuel content material, which it detects mechanically.
“If you put more ethanol in fuel, its chemical properties change and therefore the engine management system has to be able to adapt, and older cars might not be able to do that,” he stated.
By manner of resolution, he stated mechanics may rapidly join the unit to a pc and replace the fuel composition setting.
However, one senior business govt instructed The Hindu that autos that don’t have digital management items and injectors can’t be made appropriate with E20 as fuel. The govt stated “about 95%” of all autos till the rollout of the BS-VI emission requirements (in April 2020) have been mechanically carbureted, which means they didn’t utilise any digital items with sensors to control the supply and therapy of fuel.
“When the blending happens, it alters the stoichiometric ratio, i.e. air-to-fuel ratio, which in turn affects the speed of combustion and heat release,” Kuppili stated. “Modern vehicles have sensors called electronic control units, which monitor the oxygen content and alter the amount of fuel and air needed.”
With ethanol-blended petrol, he added, “you would need less air than usual, as ethanol has an oxygen atom. So this reduction can actually reduce pollutant emissions such as NOX, PM, and CO.”
“The ethanol-blending policy itself is excellent. It has been successful in other parts of the world,” Varghese stated. “The ideas of energy security and saving import duty are excellent and true. It just needs to be paced better.”
The precept of recalibration
The govt stated the sensor’s important objective is to handle the spark timing — which determines the discharge sample of the fuel and combustion contained in the cylinder. The digital management unit makes use of the spark plug to create the spark that ignites the fuel-air mix within the combustion chamber. Older autos, i.e. these missing the unit, have been tuned to a unique fuel and are thus hard-coded for a unique spark timing.
Since E20 brings extra oxygen to the fuel-air combine, the manager defined, engines could need to be recalibrated by, amongst different measures, advancing the strain for combustion and its eventual timing by two to 3 levels. In different phrases, the engine must make sure that combustion occurs earlier in order that there are not any points with beginning the car and with sustaining an sufficient air-fill ratio throughout all load situations and speeds.
This customisation isn’t doable with mechanically carbureted autos.
The govt additionally affirmed that the adjustment would enhance price.
“You have to pay the calibration engineer and the vehicle component engineers,” he stated. The latter “charge good money.”
(With inputs from Saptaparno Ghosh)
